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Journal of Bionic Engineering 2021年第1期18卷 30-39页

作者： Mei Zhang Wanghuai Xu Minfei Li Jiaqian Li Peng Wang Zuankai Wang Department of Mechanical Engineering City University of Hong KongHong Kong999077China Department of Civil and Environmental Engineering the Hong Kong Polytechnic UniversityHong Kong999077China

The development of water purification device using solar energy has received tremendous *** extensive progress,traditional photothermal conversion usually has a high cost and high environmental *** overcome this problem,we develop a low cost,durable and environmentally friendly solar *** bilayered evaporator is constructed with a thermal insulating polyvinylidene fluoride(PVDF)membrane as a bottom supporting layer and plasmonic silver nanoparticles decorated miero-sized hybrid flower(Ag/MF)as a top light-to-heat conversion *** with the sample with a flat silver film,the two-tier Ag/MF has a plasmonic enrichment property and high efficiency in converting the solar light to hcat as cach flower can gencrate a microscale hotspot by enriching the absorbed solar *** the other hand,the PVDF membrane on the bottom with porous structure not only improves the mechanicalstability of the entire structure,but also maintains a stable water supply from the bulk water to the evaporation interface by capillarity and minimizes the thermal *** combination of excellent water evaporation ability simple operation,and low cost of the production process imparts this type of plasmonic enhanced solar-driven interfacial water evaporator with promising prospects for potable water purification for point-of-use applications.

关键词： bionic plasmonic water evaporation synergistic effect Ag NPs hybrid flower

Electrophoretically deposited binder-free 3-D carbon/sulfur nanocomposite cathode for high-performance Li–S batteries

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Journal of Energy Chemistry 2020年第9期29卷 92-101,I0003页

作者： Sasan Ghashghaie Samson Ho-Sum Cheng Jie Fang Hafiz Khurram Shahzad Robin Lok-Wang Ma Chi-Yuen Chung Department of Materials Science and Engineering City University of Hong KongHong KongChina Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyHong KongChina

In the present study,the electrophoretic deposition method was successfully applied as a binder-free and scalable approach to deposit carbonaceous nanomaterials on carbon fiber paper(CFP)for cathode applications in Li-S *** microstructural studies of the EPD-CNT film using scanning electron microscopy(SEM)revealed the formation of a crack-free and porous layer of CNTs being uniformly distributed on the CFP *** EPD:CFP/CNT/S cathode delivered a capacity around 2.2 times higher than that obtained in the absence of the EPD-CNT film(CFP/S cell)after 50 cycles and a capacity of935 mAh g^-1 after 100 cycles at 0.1 *** EPD method was then employed to fabricate layer-by-layer structures where the EPD-CNT film was decorated with carbon black *** initial capacity as well as the reversible capacity after 100 cycles was further increased by the EPD:CFP/CNT/KB/S layer-by-layer structure to 1473 and 1033 mAh g^-1,respectively,indicating effective suppression of the shuttle *** addition,the rate performance of CFP/S was improved by depositing the EPD-CNT and EPD-CNT/carbon black architectures on CFP surface,and even further enhanced through the co-deposition of CNT and Pt nanoparticles by EPD,delivering a specific capacity of around 730 mAh g^-1 at 1 ***,the cathodes fabricated by EPD were observed to outperform those made by the conventional casting method in terms of cycling performance,internal resistance,and *** difference was ascribed to the non-uniform microstructure of the Cast-CNT film,which resulted in poor interfacial connection between the CNT agglomerates,hindering uniform sulfide/sulfur deposition during *** obtained results suggested that the binder-free C/S nanocomposite cathode made by EPD is key to further enhance the specific capacity and energy density of Li-S batteries.

关键词： Electrophoretic deposition Lithium-sulfur batteries Carbon nanotubes C/S nanocomposite

Compressive elastic behavior of single-crystalline 4H-silicon carbide(SiC) nanopillars

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Science China(Technological Sciences) 2021年第1期64卷 37-43页

作者： FAN SuFeng LI XiaoCui FAN Rong LU Yang Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Nanomanufacturing Laboratory(NML) Center for Advanced Structural Materials(CASM)City University of Hong Kong Shenzhen Research InstituteShenzhen 518057China

As a wide-bandgap semiconductor, 4H-SiC is an ideal material for high-power and high-frequency devices, and plays an increasingly important role in developing our country’s future electric vehicles and 5G techniques. Practical applications of SiCbased devices largely depend on their mechanical performance and reliability at the micro-and nanoscales. In this paper, singlecrystal [0001]-oriented 4H-SiC nanopillars with the diameter ranging from ~200 to 700 nm were microfabricated and then characterized by in situ nanomechanical testing under SEM/TEM at room temperature. Loading-unloading compression tests were performed, and large, fully reversible elastic strain up to ~6.2% was found in nanosized pillars. Brittle fracture still occurred when the max strain reached ~7%, with corresponding compressive strength above 30 GPa, while in situ TEM observation showed few dislocations activated during compression along the [0001] direction. Besides robust microelectromechanical system(MEMS), flexible device and nanocomposite applications, the obtained large elasticity in [0001]-oriented 4H-SiC nanopillars can offer a fertile opportunity to modulate their electron mobility and bandgap structure by nanomechanical straining,the so called "elastic strain engineering", for novel electronic and optoelectronic applications.

关键词： silicon carbide elastic deformation compressive behavior in situ SEM/TEM elastic strain engineering

Effectiveness of air cleaner on mitigating the transmission of respiratory disease in a dental clinic environment

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Building Simulation 2024年第10期17卷 1789-1803页

作者： Gang Yang Yifan Wang Ka Chung Chan Kwok Wai Mui Thomas F.Flemmig SThomas Ng Christopher Y.H.Chao Sau Chung Fu Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Faculty of Dentistry The University of Hong KongHong KongChina Department of Architecture&Civil Engineering City University of Hong KongHong KongChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina

In dental clinics with an open floor plan,the risk of patient-to-patient transmission of respiratory disease is a *** dental procedures large amounts of bioaerosol are produced and patients cannot wear personal protective *** paper examines how to effectively deploy air cleaner to reduce the infection risk in dental clinics with an open floor *** locations of air cleaners at various clean air delivery rates(CADRs)were *** dispersion of bioaerosol was studied through numerical simulations,and risk assessment was performed by a dose-response *** findings indicated that dental patients downstream of the background ventilation have a higher infection risk than those to the left and right of an infected patient(i.e.,the source).The lowest infection risks for the adjacent patients were found when the air cleaner was place opposite to the dentists,i.e.,on the floor at low CADR levels of 2.2 m^(3)/min or on the bench at CADR levels of 4.4 m^(3)/min or *** results of this study indicated that air cleaner can mitigate the risk of patient-to-patient transmission of SARS-CoV-2 in dental clinics with an open floor *** CADR levels determine the optimal placement of air cleaners.

关键词： infection risk air cleaner location dental clinic CFD simulation respiratory disease

Laser-Induced Graphene:En Route to Smart Sensing

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Nano-Micro Letters 2020年第11期12卷 209-225页

作者： Libei Huang Jianjun Su Yun Song Ruquan Ye Department of Chemistry City University of Hong KongKowloonHong KongPeople’s Republic of China State Key Lab of Marine Pollution City University of Hong KongKowloonHong KongPeople’s Republic of China

The discovery of laser-induced graphene(LIG) from polymers in 2014 has aroused much attention in recent years.A broad range of applications,including batteries,catalysis,sterilization,and separation,have been *** advantages of LIG technology over conventional graphene synthesis methods are conspicuous,which include designable patterning,environmental friendliness,tunable compositions,and controllable *** addition,LIG possesses high porosity,great flexibility,and mechanical robustness,and excellent electric and thermal *** patternable and printable manufacturing process and the advantageous properties of LIG illuminate a new pathway for developing miniaturized graphene *** use in sensing applications has grown swiftly from a single detection component to an integrated smart detection *** this minireview,we start with the introduction of synthetic efforts related to the fabrication of LIG ***,we highlight the achievement of LIG sensors for the detection of a diversity of stimuli with a focus on the design principle and working *** development of the techniques toward in situ and smart detection of multiple stimuli in widespread applications will be discussed.

关键词： Laser-induced graphene Smart sensor Printable electronics Design principle

Intrinsic superflat bands in general twisted bilayer systems

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Light(Science & Applications) 2022年第7期11卷 1475-1481页

作者： hongfei Wang Shaojie Ma Shuang Zhang Dangyuan Lei Department of Materials Science and Engineering City University of Hong KongKowloonHong Kong 999077China Department of Physics University of Hong KongHong Kong 999077China Department of Electrical and Electronic Engineering University of Hong KongHong Kong 999077China

Twisted bilayer systems with discrete magic angles,such as twisted bilayer graphene featuring moirésuperlattices,provide a versatile platform for exploring novel physical ***,we discover a class of superflat bands in general twisted bilayer systems beyond the low-energy physics of magic-angle twisted *** considering continuous lattice dislocation,we obtain intrinsic localized states,which are spectrally isolated at lowest and highest energies and spatially centered around the AA stacked region,governed by the macroscopic effective energy potential *** localized states exhibit negligible inter-cell coupling and support the formation of superflat bands in a wide and continuous parameter space,which can be mimicked using a twisted bilayer nanophotonic *** finding suggests that general twisted bilayer systems can realize continuously tunable superflat bands and the corresponding localized states for various photonic,phononic,and mechanical waves.

关键词： properties. twisted bands

Searching for Best Network Topologies with Optimal Synchronizability:A Brief Review

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IEEE/CAA Journal of Automatica Sinica 2022年第4期9卷 573-577页

作者： Guanrong Chen IEEE the Department of Electrical Engineering City University of Hong KongHong KongChina

The Laplacian eigenvalue spectrum of a complex network contains a great deal of information about the network topology and dynamics,particularly affecting the network synchronization process and *** article briefly reviews the recent progress in the studies of network synchronizability,regarding its spectral criteria and topological optimization,and explores the role of higher-order topologies in measuring the optimal synchronizability of large-scale complex networks.

关键词： Complex network higher-order topology spectral analysis synchronizability total homogeneity

A LQP BASED INTERIOR PREDICTION-CORRECTION METHOD FOR NONLINEAR COMPLEMENTARITY PROBLEMS

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Journal of Computational Mathematics 2006年第1期24卷 33-44页

作者： Bing-sheng He Li-zhi Liao Xiao-ming Yuan Department of Mathematics Nanjing University Nanjing 210093 China Department of Mathematics Hong Kong Baptist University Hong Kong China Department of Mathematics City University of Hong Kong Hong Kong China

To solve nonlinear complementarity problems （NCP）, at each iteration, the classical proximal point algorithm solves a well-conditioned sub-NCP while the Logarithmic-Quadratic Proximal （LQP） method solves a system of nonlinear equations （LQP system）. This paper presents a practical LQP method-based prediction-correction method for NCP. The predictor is obtained via solving the LQP system approximately under significantly relaxed restriction, and the new iterate （the corrector） is computed directly by an explicit formula derived from the original LQP method. The implementations are very easy to be carried out. Global convergence of the method is proved under the same mild assumptions as the original LQP method. Finally, numerical results for traffic equilibrium problems are provided to verify that the method is effective for some practical problems.

关键词： Logarithmic-Quadratic proximal method Nonlinear complementarity problems Prediction-correction Inexact criterion

Pinning Control and Controllability of Complex Dynamical Networks

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International Journal of Automation and computing 2017年第1期14卷 1-9页

作者： Guanrong Chen Department of Electronic Engineering City University of Hong Kong Hong Kong China

In this article, the notion of pinning control for directed networks of dynamical systems is introduced, where the nodes could be either single-input single-output （SISO） or multi-input multi-output （MIMO） dynamical systems, and could be non-identical and nonlinear in general but will be specified to be identical linear time-invariant （LTI） systems here in the study of network controllability. Both state and structural controllability problems will be discussed, illustrating how the network topology, node-system dynamics, external control inputs and inner dynamical interactions altogether affect the controllability of a general complex network of LTI systems, with necessary and sufficient conditions presented for both SISO and MIMO settings. To that end, the controllability of a special temporally switching directed network of linear time-varying （LTV） node systems will be addressed, leaving some more general networks and challenging issues to the end for research outlook.

关键词： Complex network pinning control controllability linear time-invarJant (LTI) system temporally switching network,graph theory.

Schematic interface of sound creation for computer animators

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2006年第7期7卷 1141-1151页

作者： TONG Kam-pang Maya WONG Kam-wah School of Creative Media City University of Hong Kong Hong Kong China

As an audiovisual medium, computer animations require superior image quality and professional soundtrack to lead audiences into their fascinating virtual world. Without sound, the impact of storytelling is reduced or the story is even not under- standable. Despite the importance of sound, most animators are unfamiliar with sound editing software. Limited budget projects such as independent or student works have difficulty hiring sound professionals to create tailor-made soundtrack. Therefore, we need a suitable sound tool to express their individual ideas. In this paper, we propose an approach using schematic for both computer animation and sound. Our approach provides (1) physical simulation on sound through animation parameters and (2) a new channel for animators to add aesthetic values in sound through their experience of using schematics in existing animation software. We demonstrate our idea through several examples, such as Doppler shift, obstacle effect, importance, energetic, and sputtering effect.

关键词： Computer animation Multimedia Digital media Schematics Physical simulation Aesthetic Sound effects Soundtrack